We keep learning more about the Jan. 6, 2021, attack on the U.S. Capitol. And we keep learning more about the many schemes former President Trump and his team tried to use to overturn the 2020 presidential election.

In some ways, it is discouraging. We know just how badly Mr. Trump’s inner circle was corrupted by his desire to keep power at all costs. We had lawyers writing memos about how to break the law and stop Congress from affirming Mr. Trump’s defeat. We had members of Congress repeating his lies about a stolen election and trying to take the decision away from the voters.

In other ways, it is encouraging that the truth continues to come out. News stories that expose lies and corruption remind us of the importance of a free press. The investigation by the Jan. 6 select committee reminds us how much we need the checks and balances that are built into our system.

Those checks and balances — like the ability of Congress to conduct oversight of the Executive Branch — are necessary to prevent abuses of power and hold politicians accountable.

But for those protections to work, we must have public officials who are committed to upholding the rule of law. That’s not what we’re seeing from former Trump staffers and advisers. Just the opposite. They are stonewalling the congressional investigation and defying its subpoenas.

And with just a few exceptions, congressional Republicans are not acting honorably. Rather than embracing the search for truth, they try to discredit the investigation. Rather than face up to the anti-democratic rot in their party, they would like to sweep it all under the rug.

Let’s be clear. Mr. Trump and his law-breaking friends are trying to keep Americans from learning the truth about the attack on Congress and the attempt to overthrow the will of the voters.

Specifically, Mr. Trump and his supporters are trying to run out the clock. They are counting on their allies taking a majority in the House of Representatives in this year’s elections. And then they’ll shut the investigation down before the full truth can come out.

That would be disastrous for our democracy.

Consider just a few of the things we have learned recently.

When the White House handed over logs of Mr. Trump’s calls on the day of the insurrection, there was a seven-hour gap covering the crucial hours before, during and after the attack on Congress. What violations of law are hiding in that gap?

We also learned that Ginni Thomas, a hard-right activist and wife of U.S. Supreme Court Justice Clarence Thomas, was in regular contact with Mr. Trump’s chief of staff Mark Meadows in the days and weeks after the presidential election. She embraced even the most extreme and ridiculous far-right conspiracy theories about the election. She even said she hoped it was true that members of the “Biden crime family,” reporters and elected officials were being arrested and would be held on barges in Guantanamo Bay to face military trials for sedition. She urged Mr. Trump not to concede defeat.

It just so happens that Justice Thomas was the only U.S. Supreme Court justice who backed Mr. Trump’s attempt to keep White House records from being shared with the Jan. 6 committee. It was an 8-1 vote. That explains why so many people are now calling on Justice Thomas to resign — or at the very least to recuse himself from any other cases about the insurrection that come before the court.

We can’t make Justice Thomas act honorably. But that doesn’t mean we are powerless to protect our democracy.

It was we the people who voted Mr. Trump out of power. Mr. Trump’s ability to pressure and bully election officials and legislators into joining his corrupt schemes was limited by the fact that he lost in multiple battleground states, not just one. His supporters’ ability to shield him from accountability will be determined in part by what happens in this year’s elections.

When Americans go to the polls this fall to elect members of Congress, we will not only be participating in democracy, we will be determining its future.

The writer, a former national president and chief executive officer of the NAACP, serves as president of People for the American Way. He also teaches leadership at the University of Pennsylvania.